The aim of this study was to explore the impact of out-of-pocket costs on Dutch general practitioners' prescribing. A qualitative study using focus groups was conducted. An open-ended topic guide was used to elucidate the influence of out-of-pocket costs on decision making for the treatment of dyspepsia, hay fever, hormone replacement therapy, and hypertension. A total of 21 Dutch GPs from University Departments of General Practice participated in four separate focus groups. These discussions were held between November 1998 and March 1999. Each discussion was tape-recorded and transcribed verbatim. From this transcription, key factors and issues were identified. GPs reported that they do not generally take out-of-pocket costs into account. Fully reimbursed drugs were usually prescribed and GPs felt that most patients were highly motivated and thus willing to pay for their medication. The patient charges were seen to be low and not likely to affect patients' willingness to pay. GPs felt that patients need not have to pay for their medication. They adjusted their drug choice in order to avoid co-payment and were willing to agree to a patient's demand for a reimbursed prescription. GPs describe their prescribing as not influenced by out-of-pocket costs. GPs seem inclined to avoid co-payment for patients when patients have financial difficulties and the disease is perceived as severe. They chose fully reimbursed drugs.